That's the CPU FSB freq and with the multiplicator that would result to the speed of your CPU. It's like overworking your processor. You could keep it at 300 but it would make your CPU hotter, and there is big probability that it will shorten the lifespan of your CPU, and damage it eventually. If you keep it at 300 FSB make sure your CPU is well ventilated if not with a water cooling system.
I have a MSI K89 Neo Motherboard with a AMD 2800 64 bit processor, and in my bios it has a thing that says CPU FSB FREQUENCY and its set at 200 but it can go up by ones clear to 300 . My question is, is that my front side bus ive been hearing about so much, and what should i set it at, or should i keep it at 200?. Also with over clocking, is it a big possibility i can ruin my processor thanks .